| Name | Position | Party | Constituency |
|---|---|---|---|
| Fergus O'Dowd | TD | Fine Gael | Louth |
| Cat O'Driscoll | Councillor | Social Democrats | Cabra - Glasnevin |
| Peggy O'Dwyer | Councillor | Fine Gael | Newbridge |
| Tracey O'Dwyer | Councillor | Fine Gael | Newbridge |
| Damian O'Farrell | Councillor | Independent | Clontarf |
| Terry O'Flaherty | Councillor | Independent | Galway City East |
| Frank O'Flynn | Councillor | Fianna Fáil | Fermoy |
| Kenneth O'Flynn | Councillor | Fianna Fáil | Cork City North East |
| Pat O'Gorman | Councillor | Fianna Fáil | Shannon |
| Roderic O'Gorman | TD | Green Party | Dublin West |
| Rosaleen O'Grady | Councillor | Fianna Fáil | Sligo-Strandhill |
| PJ O'Hanlon | Councillor | Fianna Fáil | Carrickmacross-Castleblayney |
| Kieran O'Hanlon | Councillor | Fianna Fáil | Limerick City North |
| Shirley O'Hara | Councillor | Fine Gael | Clondalkin |
| John O'Hara | Councillor | Fine Gael | Ballina |